In a blog post, Tesla says that it'll finally start offering battery swaps for the Model S — a feature that was first demonstrated in mid-2013, designed as a quicker alternative to charging. The concept is that a complete battery swap, which was promised to take as little as 90 seconds, would be far faster than charging even with an ultra-fast Supercharger, so you could be in and out of a station in roughly the same amount of time (if not less) than filling up with gas.

This isn't a full deployment, though: Tesla will only be offering swaps at a special facility across the street from an existing Supercharger in Harris Ranch, California, in order to "to test technology and assess demand." It'll only be available by appointment — you can't just drive up and ask for a new battery — and the process now takes three minutes rather than the 90 seconds that had previously been suggested due to the extra battery armor that was recently added. The procedure will cost "slightly less than a full tank of gasoline." By contrast, use of Tesla's Superchargers is free.The company says that it thinks it could get the process down to under one minute with "further automation" and changes to the cars, but it's going to wait to find out just how much demand exists for the swaps before devoting engineering resources to it.